Creating the Policy File

In this example, we save this to an XML file named "policy.xml". This is then placed next to the corresponding update site.xml. This effectively says "when I see feature with id x, instead go to update site y rather than the default". You can also use wildcards, such as feature.id.* if you have multiple features with the same prefix.

Using the Policy File

The next time you search for updates, it should use the new URL specified in the policy file.

An additional thought is to provide a preference page to allow the end user to choose which "release stream" they wish to subscribe to. In this case, there is a radio button that might specify "stable", "rc" and "nightly". Selecting one of these radio buttons would automatically set the policy file behind the scenes.